1. Field of the Invention
This invention relates generally to video signal reproducing apparatus and, more particularly, is directed to a device for selecting the mode of operation in a video signal reproducing apparatus.
2. Description of the Prior Art
When an existing magnetic video tape recorder (VTR) of the helical scan type is operated in its reproducing or playback mode with a time base corrector, the speed at which the tape is transported or moved longitudinally between the supply and take-up reels may be varied while the rotary magnetic heads are rotated at the frame frequency so as to provide, on a monitor, a still, slow-motion or fast-motion reproduced picture in dependence on the speed of movement of the tape. Known VTRs have conventionally utilized electric circuits including, for example, an electro-magnetic clutch or a plunger-type solenoid, for selecting the above modes of operation, in addition to the rewind mode. Although such arrangements are relatively simple in construction, the electric circuits utilized therein are relatively expensive. It has also been proposed to utilize mechanical mode selectors for selecting predetermined modes of operation. However, such latter selectors are inferior in operation to the aforementioned electric circuits and tend to be of a relatively large size, thereby occupying excessive space and resulting in a more expensive arrangement. Further, with such mechanical arrangements, it is difficult to add functions to the apparatus and accordingly, only minimum requisite functions are provided.
Further, in many instances, it is desirable to manually control the speed and direction of movement of the tape. Accordingly, a so-called "joy-stick" control knob or lever has been provided for controlling the speed and direction of movement of the tape in dependence on the movement of the control knob. For example, in U.S. Pat. No. 4,161,001, which issued on July 10, 1979 and which has a common assignee herewith, the speed and direction of movement of the tape is controlled in accordance with the rotational speed and direction of a manually actuable control knob. On the other hand, in U.S. Pat. No. 4,139,872, which issued on Feb. 13, 1979 and which also has a common assignee herewith, the speed and direction of the tape is controlled in dependence on the angular extent and direction of a manually actuable control knob from a neutral position at which movement of the tape is halted. A VTR provided with the foregoing so-called "joy stick" control may be used for arbitrarily selecting a particular track on a tape at which a reproducing operation is to be commenced, for example, as during editing of the tape.
It should be appreciated that the manually actuable control knobs in the aforementioned VTRs operate in a different manner from each other. In particular, in the latter U.S. Pat. No. 4,139,872, continuous movement of the tape at a desired speed can be controlled without the necessity of the operator continuously rotating the manually actuable control knob. However, with such arrangement, it becomes difficult to accurately stop the tape with a selected track precisely positioned for scanning by the rotary magnetic heads since, to do so, requires repeated to and fro displacements of the control knob. The former U.S. Pat. No. 4,161,001, which controls the speed and direction of movement of the tape in accordance with the speed and direction of rotation of the control knob, cures this deficiency. However, as to the former operation, that is, for controlling movement of the tape continuously at a desired speed, the control knob must be manually rotated at a constant speed which, of course, becomes extremely difficult, if not impossible. It is therefore desirable to provide a control knob which combines both of the above operations into a single mechanism.